that doesn’t really make much sense. Sure the deltas will arise when you go near fire but most cases the temperature is a function of the weather. Plus, adding checks on deltas is reworking the internal mechanics.
Right now, temperature is applied to the bodyparts and then clothing is used to provide warmth. If the resulting number is in the comfortable range, then we’re good. If you have to keep track of deltas, now you have to have some sort of history of which deltas were applied so that you can have consistent temperature as you, say, enter and exit a building in winter.
I can already forsee some weird exploit of entering buildings, unequipping or equipping clothing and exiting buildings to get your warmth down to the point where you can run around in heavy survivor armor in the summer. I don’t think using deltas is the right idea.
The previous idea of using an insulation value and a warmth value which pretty much respectively decreases and increases warmth is most likely the solution here, but figuring out when insulation is applied and such is where the aforementioned maths comes in. I guess the naive approach is just
if temp > 25
warmth = ceil(25, temp - insulation)
else warmth = <regular temp calculations>
which would be incredibly shit and probably a massive oversimplification of how the temperature system works.
Another tangentially related thing, the characters in cataclysm are terrible when it comes to hot weather. They feel hot when the air temperature is 24 and they’re wearing mostly nothing. As an Australian, 24 is what I set my air conditioning to. If the air temp is 24, I can comfortably sleep under my quilt.